Rearing and Biology of Wohlfahrtia vigil (Diptera: Sarcophagidae)1

Abstract

Many generations of Wohlfahrtia vigil (Walker) were reared on young domestic rabbits, and 5 generations on an artificial medium containing blood and ground beef, from larvae deposited in a collection dish in a box containing a mouse. Flies reared on the medium appeared biologically equal to those reared on rabbits. Larvipositing flies were more strongly attracted to an adult mouse than to a litter of 10 young mice, a young pigeon, or larval medium plus CO2; to young mice than to a young pigeon; to CO2 than to air alone; to mouse odor plus CO2 than to either one alone; and to larval medium plus CO2 than to either medium alone or water plus CO2. They showed no response to a visible mouse enclosed in an airtight container, but in ventilated containers a visible mouse was significantly more attractive than a hidden one. A pattern of black-and-white squares was significantly more attractive than a white surface. Although host-finding by Wohlfahrtia may involve both airborne and visual factors, the former appeared of greatest importance. Adult animals or their abodes appeared attractive to larvipositing flies, although larvae ordinarily can survive only on the young. In nature, a variety of mammals and birds are apparently subject to attack; but observations on cottontail rabbits, both in the laboratory and under penned, seminatural conditions, indicated that they may be a major host of W. vigil. The severe outbreak of myiasis in commercial mink in Wisconsin in 1959 may have resulted from the combination of favorable weather (warm temperatures in May and June) following a sharp decline in the wild rabbit population.